沖縄自然写真 By Shawn Miller

Main menu

Tag Archives: Environmental impact

Invasive species are introduced animals, plants and fungus that cause damage to the natural environment. Non-native species have a tendency of dominating the habitat and eventually wiping out native wildlife. They have been deliberately or accidentally introduced and generally do more harm than good.

The mongoose was introduced to Okinawa in 1910 in attempt to control the population of venomous snakes. The problem is the habu snake is nocturnal and the mongoose is diurnal, so they rarely meet.

Mongoose ( Hepestes javanicus ) -Nagahama, Okinawa

The pheasant was introduced in the 1900′s as a food source. The bird is also know to feed on small snakes and insects that feed on local crops.

Common Pheasant – Yomitan, Okinawa

The Red eared turtle was Introduced in the the 1960′s. Pet owners generally release these turtles when they get too big.

Red-eared slider -Nagahama, Okinawa

The White jawed frog was introduced in the the 1960′s. It was brought in by the pet trade or hitchhiking on shipping supplies.

White lipped tree frog – Ie Island

The Taiwanese habu was introduced in the 1970s for zoo exibitions and medicine. They are fairly common in Onna village.

Taiwanes habu- Onna village

The Apple snail was introduced as a food source in the 1980s. They are commonly found in rice fields. It’s not recommended to handle or eat these snails raw. They sometimes carry parasites that cause disease.

Apple snail -Kunigami, Okinawa

Feral cats are master hunters. They are responsible for killing native species such as birds, lizards and mice. Some countries have implemented programs to reduce the killing of wildlife. If you own a cat that spends it time outdoors, it is recommended to place a brightly colored collar with a bell on it. This warns the native wildlife and gives them a chance to escape.

Feral cats – Kin, Okinawa

The american bullfrog was introduced in 1918 as a food source. Bullfrogs eat anything they can fit into their mouth. They are larger and overpower the native frogs of the Ryukyu Islands.

American bullfrog – Izena Island

The Giant African snail was Introduced as a food source in the 1930′s . It’s not recommended to handle or eat these snails raw. They sometimes carry parasites that cause disease.

Giant African snail -Kin, Okinawa

The Coconut rhinoceros was introduced with the importation of palm trees.

Coconut rhinoceros beetle

The Snapping turtle was introduced by pet owners. They buy them when they are very small and fail to realize they can live for over forty years.

Snapping turtle – introduced to okinawa

The Taiwanese beauty snake was introduced in the 1970s for zoo exhibitions.

Taiwanese beauty snake – Yomitan, Okinawa

The Brown rat was possibly introduced by lumber transportation ships.

Brown rat (Rattus norvegicus) -Yomitan, Okinawa

Talapia were brought to the Ryukyu islands in the 1960s as a food source. They eat the eggs of amphibians and compete with native fish.

Featured

Crabs with beach trash homes is a series I am currently working on. I photograph Blueberry hermit crabs (Coenobita purpureus) that have begun to use beach trash as their home. The crabs are photographed in their nature environment and also on white for the Meet Your Neighbours global biodiversity project. The images are used for environmental awareness and educational purposes.

Hermit crabs with beach trash homes

Blueberry hermit crabs are commonly found on local beaches in Okinawa. Most crabs are blue but occasionally have color variations of purple, pink, orange and or gray. They prefer to have a seashell as a protective home but when no shell is available they adapt.

It’s becoming more common to find crabs with beach trash homes. I have friends combing local beaches in search of more crabs for my series. While these are cute images, our trash is becoming a serious problem to the ocean and the animals that call the shoreline home. I often find hermit crabs using a variety of plastic caps from twist top pet bottles, laundry detergent containers, small propane tanks, sports water bottles and beauty supplies.

Possible reason why Blueberry crabs adapt with beach trash

Limited number of available shells causing them to make due with the best homes they can find. This is a good example of adaptive behavior.

Hermit crabs are very social animals and often fight over shells. Having a protective lightweight shell that covers the abdomen (soft parts of the animal) is crucial for survival.

Hermit crabs fighting over prime real estate

The battle -

A close-up of the sensitive abdomen (photographed using the MYN technique)

Naked hermit crab

Hermit crabs are scavengers and take advantage of any food washed ashore. They mainly feed on dead fish, barnacles, other crabs, algae, insects, plants, fruit and various seeds. The screw pine (Pandanus odifer) is one of their favorite foods. I imagine long ago these vital plants lined our shorelines in abundance. Numbers are decreasing due to deforestation.

Pandanus odifer

Eventually the fruit drops to the ground and the sweet smell attracts the hermit crabs

Hermit crab feeding

The hermit crabs feed on the the fresh keys and help with seed dispersal. They both benefit in this relationship. The Pandanus tree provides shelter, shade, food for the hermit crabs.

Hermit crab and Pandanus

Eventually the keys dry, turn brown and litter the local beaches. The dispersed keys provide a perfect environment for hermit crabs to blend in with.

Where the treeline meet the beach

Hermit crabs prefer to be in a shell that protects the entire body from predators. Sometimes they have to temporarily adapt with a much smaller shell. The retracted hermit crab tightens up to protect itself. Ball up, play dead and blend into the environment, minimizing the risk of being preyed upon.

Could this be a form of masquerading or just coincidence ? It resembles (mimics) the shape of the screw pine seed to possibly avoid detection from potential predators.

Hermit crab and screw pine seed

Hermit crabs have the ability to ball up tight to protect their eyes. (Transformers)

Hermit crab retracted

Below are some of my favorite images photographed on a portable field studio board (MYN Technique). The crabs are safely placed on a white studio board, photographed and released back into the natural environment (MYN Technique).

Blueberry hermit crab (Coenobita purpureus) with cap

Blueberry hermit crab (Coenobita purpureus) in plastic tube

Blueberry hermit crab (Coenobita purpureus) in plastic top cap

Blueberry hermit crab (Coenobita purpureus) in plastic

Blueberry hermit crabs (Coenobita purpureus) in plastic cap

Blueberry hermit crabs (Coenobita purpureus) in plastic top cap

Blueberry hermit crab- Ryukyu Islands

Blueberry hermit crab – Okuma, Okinawa

It’s important to photograph the hermit crabs in their natural habitat. I prefer to photograph them using a wide angle lens to achieve a unique perspective.

Meet zori -Wide angle macro

Hermit crab- Plastic pollution

Blueberry hermit crab, Wide angle macro

Meet scoop- Quaker

Meet shady – Worldwide trash problem

Hermit crab in a glass bottle- Yomitan, Okinawa.

Meet cassette -CWBTH

Airplane -Senaga Island ,Okinawa

Land hermit crab, Onna-Okinawa

Meet sparky- using a plastic cap from a cassette gas tank

Energy drink home- Trash homes

The rock climber -Northern Okinawa

Sunset Time – Yomitan ,Okinawa

Beach pollution- CWBTH

Tree climber-

Plastic pollution – beach trash

Crabs and plastic – WAM

Got Meds -Beach trash

Get off the road jack -

Crabs and plastic -Onna Village

I also photograph the hermit crabs using a dedicated macro lens. I mainly use the Canon 60 mm or 100 mm macro lens to concentrate on the subject. These crabs are fairly small and it’s important to have a lens that will focus close and deliver high quality sharpness.

Meet Edison- Gobe700

Meet hand -toy end cap

Beach trash -hermit crabs

Blueberry hermit crab, Okuma-Okinawa

Laundry detergent cap – Northern Okinawa

Cassette gas tank cap – bbq beach party

White cap on drift wood

Meet scoop-

Blueberry hermit crab, Hedo-Okinawa

Meet Edison -Gobe700

Blueberry hermit crab, Onna-Okinawa

Blueberry hermit crab, Hedo-Okinawa

School project ” Crabs with beach trash homes ” My family and I collected trash on a local beach in Onna village. This is just a small portion of our beach trash findings. The kids did a great job creating a project with impact.

Kirana’s school project

Kyle’s school project

Behind the scenes photograph ” Crabs with beach trash homes ” I have documented over sixty crabs with beach trash homes. If you would like to see more images check out my Flickr account.